In electrophotographic type image forming apparatuses, an image is formed by fixing a toner image, which is transferred on a sheet, onto the sheet by heating and pressing the toner image. As a fixing device for performing the fixing, there is a type composed of a heating roller that is heated and a pressure roller that is in contact with the heating roller by predetermined pressure or a type composed of a heating belt suspended on a roller and heated and a pressure roller opposite to the heating belt.
In the related art, when fixing is performed by the fixing device, the surface opposite to the fixed surface in both surfaces of a sheet is occasionally tainted.